The Jamestown-Scotland Ferry has helped Virginians and their vehicles cross the James River for free, 24 hours a day since 1925. The Virginia Department of Transportation (VDOT) took over ferry operations in 1945, and currently transports nearly a million vehicles annually.
The ferry terminals had, since their opening, used dolphins of wood piles to guide ferries to the berths. The wood piles had multiple drawbacks: They rotted over time and had to be replaced regularly; they were kept in operation through the use of creosote and other environmentally damaging chemicals; and they were subject to damage by the regular occurrence of ferries making contact with the dolphins.
Beginning in 2015, VDOT began to replace the wood pile dolphins with fiber-reinforced polymer (FRP) piles.
Background
The vessels in the Jamestown-Scotland Ferry fleet are big. The Powhatan measures 270 feet, the Pocahontas 236 feet 4 inches, and the Surry and the Williamsburg are 200 feet. Tonnages range from 360 to 1630 long tons loaded. With vessels this large, going even a little off course could have major consequences.
The right piling is essential to keep the fleet, their passengers and passengers’ vehicles safe as the ferries come into dock. In the past, dolphins comprised of anywhere from three to 50 wood piles helped berthing and mooring. These dolphins guided the ferries into the terminal without letting the vessels bump into the pier and keep vessels at the port during adverse weather conditions.
Wood, however, is not well-suited to the James River. The river lies close to the Chesapeake Bay and its water is much saltier than normal freshwater. Hydroscopic wood piles in salt water can sometimes resist microbial rot for longer than freshwater pilings. But the part-salt, part-fresh water means wood piles on the James get double damage. Weak pilings can’t keep ferries safe. In calm weather, pilings guide ferries in, but in inclement or dangerous weather, the large ferries impact the pilings during the approach to the terminal. VDOT needed to replace unsafe wood pilings sometimes yearly.
In addition, wood piles must be chemically treated to prevent decay and deterioration, chemicals that can leach into the surrounding water.
By the early 2000s, VDOT was experiencing issues with the timber dolphin clusters at the Jamestown ferry dock.
“Those clusters were breaking apart because of some of the chemicals they were treated with and because of the larger vessels that the ferry had purchased and put into use,” explained Corey Sechler, sales manager for waterfront solutions at Creative Composites Group. “In 2014, VDOT initiated a study for the phased replacement of existing timber dolphins. Starting in 2015, they started putting FRP replacement in, one or two at a time to see how they performed. That phased replacement continues to this day, as they have budget available.”
VDOT Chose Sustainable FRP Monopiles
VDOT chose to replace its aging, chemically treated wood piles with StormStrong™ monopiles manufactured by Creative Composites Group, since a single FRP monopile can replace an entire cluster of wooden piles.
FRP is an engineered material made of reinforcement fibers, polymer resin and additives that creates an extremely strong, durable material. Compared to wood, FRP exhibits excellent resistance to mildew and mold with no chemical coatings.
FRP piles maintain their structural integrity, even when submerged, without leaching chemicals into the water. FRP is man-made, which allows for on-demand production and avoids deforestation. Composite manufacturing is both cost-effective and has a lower environmental impact than extruding metals or preparing wood and concrete. And FRP is very light, reducing the number of trips – and gallons of fuel – needed to transport the material to the destination.
FRP monopiles can bend during ferry impact without breaking. The already weaker structural integrity of wood weakens significantly with each ferry impact. The unique chemistry and fiber architecture of FRP creates an engineered material that is optimized to stay strong during repeated berthing events.
Installation
FRP pilings can be installed via traditional methods, including vibration hammers and impact hammers. The same equipment used for wood and steel piles is used for FRP. Even when the pilings hit hard bedrock, FRP pilings can hammer through the rock layer or may be installed using high-pressure water jetting.
FRP’s light weight means that fewer trucks, cranes, laborers and hours must be spent transporting and installing composite pilings. The material’s light weight makes it safer to work with, and the fast installation means shorter interruptions to passengers.
Experience
Three pilings were replaced in 2017, and five were replaced in 2019 under a separate grant-funded project. The dolphin replacement project has won numerous awards, including a 2019 Virginia Transportation Construction Alliance Engineering Award and one from the World Association for Waterborne Transport Infrastructure in 2016.
More recently, the Jamestown-Scotland Ferry pilings were recently tested when a microburst hit the ferry route. The Surry side was more protected, but the more exposed Jamestown side experienced upwards of 70-mph winds. Naturally, the ferry was just mooring at the Jamestown port when the microburst began. The captain had no choice but to rest the ferry on the pilings to keep the boat and its passengers and cargo safe.
The ferry rested on the StormStrong FRP monopiles with no issues. Wood piling would lean after impact, showing it had been hit. But the FRP monopiles looked brand-new even after taking the weight of a 50,000-pound boat in almost hurricane-force winds. A staff member who witnessed the event and the aftermath said, “These pilings are doing their job way better than the wood pilings could.”
FRP’s increased structural capacity and corrosion resistance will reduce maintenance costs and extend service life. FRP can often last over 75 years with minimal or no maintenance.
VDOT’s investment in FRP monopiles has already shown significant returns. The fleet and its passengers are safer, and far fewer taxpayer dollars go to replacing rotting wood piles every year.
Reprinted from Marine Construction Magazine, Issue II, 2024
